It all depends on who's affected and what the extent of the damage would be to said countries.

A big war right now would throw a large portion of the world into shambles for a while, and the longer it goes on the significantly more damaging it will be. As long as the internet is operating, Bitcoin will be able to proliferate, but there are so many individual variables that can affect whether or not Bitcoin would be good that it's next to impossible to determine either way.